Add enabled_for_attribute? method

To Gitlab::Experimentation. And add
invitation_reminders as an experiment.

lib/gitlab/experimentation.rb

@@ -62,6 +62,9 @@ module Gitlab
       },
       invite_email: {
         tracking_category: 'Growth::Acquisition::Experiment::InviteEmail'
+      },
+      invitation_reminders: {
+        tracking_category: 'Growth::Acquisition::Experiment::InvitationReminders'
       }
     }.freeze
 
@@ -94,7 +97,7 @@ module Gitlab
       def experiment_enabled?(experiment_key)
         return false if dnt_enabled?
 
-        return true if Experimentation.enabled_for_user?(experiment_key, experimentation_subject_index)
+        return true if Experimentation.enabled_for_value?(experiment_key, experimentation_subject_index)
         return true if forced_enabled?(experiment_key)
 
         false
@@ -183,9 +186,14 @@ module Gitlab
         experiment.enabled? && experiment.enabled_for_environment?
       end
 
-      def enabled_for_user?(experiment_key, experimentation_subject_index)
+      def enabled_for_attribute?(experiment_key, attribute)
+        index = Digest::SHA1.hexdigest(attribute).hex % 100
+        enabled_for_value?(experiment_key, index)
+      end
+
+      def enabled_for_value?(experiment_key, experimentation_subject_index)
         enabled?(experiment_key) &&
-          experiment(experiment_key).enabled_for_experimentation_subject?(experimentation_subject_index)
+          experiment(experiment_key).enabled_for_index?(experimentation_subject_index)
       end
     end
 
@@ -200,10 +208,10 @@ module Gitlab
         environment
       end
 
-      def enabled_for_experimentation_subject?(experimentation_subject_index)
-        return false if experimentation_subject_index.blank?
+      def enabled_for_index?(index)
+        return false if index.blank?
 
-        experimentation_subject_index <= experiment_percentage
+        index <= experiment_percentage
       end
 
       private

spec/lib/gitlab/experimentation_spec.rb

@@ -73,8 +73,8 @@ RSpec.describe Gitlab::Experimentation do
       subject { controller.experiment_enabled?(:test_experiment) }
 
       context 'cookie is not present' do
-        it 'calls Gitlab::Experimentation.enabled_for_user? with the name of the experiment and an experimentation_subject_index of nil' do
-          expect(Gitlab::Experimentation).to receive(:enabled_for_user?).with(:test_experiment, nil)
+        it 'calls Gitlab::Experimentation.enabled_for_value? with the name of the experiment and an experimentation_subject_index of nil' do
+          expect(Gitlab::Experimentation).to receive(:enabled_for_value?).with(:test_experiment, nil)
           controller.experiment_enabled?(:test_experiment)
         end
       end
@@ -85,22 +85,22 @@ RSpec.describe Gitlab::Experimentation do
           get :index
         end
 
-        it 'calls Gitlab::Experimentation.enabled_for_user? with the name of the experiment and an experimentation_subject_index of the modulo 100 of the hex value of the uuid' do
+        it 'calls Gitlab::Experimentation.enabled_for_value? with the name of the experiment and an experimentation_subject_index of the modulo 100 of the hex value of the uuid' do
           # 'abcd1234'.hex % 100 = 76
-          expect(Gitlab::Experimentation).to receive(:enabled_for_user?).with(:test_experiment, 76)
+          expect(Gitlab::Experimentation).to receive(:enabled_for_value?).with(:test_experiment, 76)
           controller.experiment_enabled?(:test_experiment)
         end
       end
 
       it 'returns true when DNT: 0 is set in the request' do
-        allow(Gitlab::Experimentation).to receive(:enabled_for_user?) { true }
+        allow(Gitlab::Experimentation).to receive(:enabled_for_value?) { true }
         controller.request.headers['DNT'] = '0'
 
         is_expected.to be_truthy
       end
 
       it 'returns false when DNT: 1 is set in the request' do
-        allow(Gitlab::Experimentation).to receive(:enabled_for_user?) { true }
+        allow(Gitlab::Experimentation).to receive(:enabled_for_value?) { true }
         controller.request.headers['DNT'] = '1'
 
         is_expected.to be_falsy
@@ -336,8 +336,8 @@ RSpec.describe Gitlab::Experimentation do
     end
   end
 
-  describe '.enabled_for_user?' do
-    subject { described_class.enabled_for_user?(:test_experiment, experimentation_subject_index) }
+  describe '.enabled_for_value?' do
+    subject { described_class.enabled_for_value?(:test_experiment, experimentation_subject_index) }
 
     let(:experimentation_subject_index) { 9 }
 
@@ -377,4 +377,32 @@ RSpec.describe Gitlab::Experimentation do
       end
     end
   end
+
+  describe '.enabled_for_attribute?' do
+    subject { described_class.enabled_for_attribute?(:test_experiment, attribute) }
+
+    let(:attribute) { 'abcd' } # Digest::SHA1.hexdigest('abcd').hex % 100 = 7
+
+    context 'experiment is disabled' do
+      before do
+        allow(described_class).to receive(:enabled?).and_return(false)
+      end
+
+      it { is_expected.to be false }
+    end
+
+    context 'experiment is enabled' do
+      before do
+        allow(described_class).to receive(:enabled?).and_return(true)
+      end
+
+      it { is_expected.to be true }
+
+      context 'outside enabled ratio' do
+        let(:attribute) { 'abc' } # Digest::SHA1.hexdigest('abc').hex % 100 = 17
+
+        it { is_expected.to be false }
+      end
+    end
+  end
 end

spec/support/helpers/stub_experiments.rb

@@ -22,10 +22,10 @@ module StubExperiments
   # Examples
   # - `stub_experiment_for_user(signup_flow: false)` ... Disable `signup_flow` experiment for user.
   def stub_experiment_for_user(experiments)
-    allow(Gitlab::Experimentation).to receive(:enabled_for_user?).and_call_original
+    allow(Gitlab::Experimentation).to receive(:enabled_for_value?).and_call_original
 
     experiments.each do |experiment_key, enabled|
-      allow(Gitlab::Experimentation).to receive(:enabled_for_user?).with(experiment_key, anything) { enabled }
+      allow(Gitlab::Experimentation).to receive(:enabled_for_value?).with(experiment_key, anything) { enabled }
     end
   end
 end